Large underground oil shale deposits are found both in the U.S. and around the world. In contrast to petroleum deposits, these oil shale deposits are characterized by their solid state; in which the organic material is a polymer-like structure often referred to as “kerogen” intimately mixed with inorganic mineral components. Heating oil shale deposits to temperatures above about 300 C for days to weeks has been shown to result in pyrolysis of the solid kerogen to form petroleum-like “shale oil” and natural gas like gaseous products. The economic extraction of products derived from oil shale is hindered, in part, by the difficulty in efficiently heating underground oil shale deposits.
Thus there is a need in the art for a method and apparatus that permits the efficient in-situ heating of large volumes of oil-shale deposits.